import java.util.Stack;

//栈是一种先进后出的结构，
public class Text {
    public static void main(String[] args) {
        Stack<Integer>stack=new Stack<>();
        //入栈
        stack.push(12);
        stack.push(13);
        stack.push(14);
        stack.push(15);
        //出栈
        stack.pop();
        //获取栈顶元素，但是不删除
        stack.peek();
        System.out.println(stack.isEmpty());

    }
}
